I'll listen to a dude spitting average lyrics with an ill flow, quicker than I'll listen to a nigga spitting genius lyrics with a modern day Prodigy flow.
Lyrics !! A hot flow don't mean shit if you have nothing to say. It seems most are checking for delivery, cadence in voice structure. Emcee's that uses their voice well and also flows well: Busta, Jay-Z, LL, Guru, Rakim, Rockness Monstah. Those with a offbeat flow but has a distinctive voice: Chuck D.